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5 109. ems, BANK monzcnou AND RELATED DEVICES.

. described.

illisirnio drn rns PATENT Quince.

-WALTER. u. MARVIN, on NEW YORK. N. Y.

Specification forming part of Letters Patent No. 53,640, dated April 3, 1866 serial whom it may concern:

Be it known that I, WALTER K. MARVIN, of

. New York, in the county of N ew York and State of New York, have invented ceriein new and useful Improvements in the lllcnufecture of iron and Steel; and I hereby declare the following to be a full, clear, and exact descripiion of one some.

' Tine object of my improvement is the production of a. metal possessing the properties which slnull render ii. adopted to the manufacinre oi safes and to many other uses in the arts in which a. very beard yet tough metal is desirable. As to safes, aside from s filling of permanent fireproof qualities, ii; should be burglenproof, non only with respect; to the loclrfloui; principally to the walls, which siiould be mode to resist the drill and hammer.

Cast or chilled iron in the use of safes has proved to be entirely worthless for that purpose. in can never be chilled liar-(l. enough to resist good steel dri will invariably cmclr. when exposed to one. fife-curse wrought iron "so easily drilled to admire of its being material for sefe-box,wbile steel is ensivgcndmben used in. large plates, le t so be tempered to that degree of hardness as to defy the aciiou of ordinary drills.

Experiments costly and numerous have led to the discovery of a composition 01 alloy which oders to an eminent degree the properties i have sought to attain. Thism-eizal, which. combines the toughness of iron and the hardness of steel, is an alloy of cast-iron, wrougfioirw, and chromium, compounded in the proportions and in the manner hereinafter To enable others to make and use myinveu tion, I shall now proceed to describe the manner in which it is or'may be carried into efi'e'ct.

In the first place I obtain chrome ore, which consists of oxide of chromium and oxide of iron,silico, and alumina, in the proportions of about the following, which is that from Chester county, Pennsylvania:

Protoxide of iron 35.14 Oxide of chromium 51.56 Alumina 9.72 Silica 2.90

This ore I pulverize and mix with rcducin g and fiuxing materials, in eboutihe following proportions: two hundred pounds pulverized chrome ore, thirty-three pounds pulverized charcoal, sevcntyfive pounds silica, thirtytliree pounds quick lime, fifty-six pounds can-- bonate of soda.

This mixture is put into on ol'diunrycruciblc generally used for melting steel, covered with a-lid, and submitted too heat. of about the some degree required for making low steel from wrought-iron for two and a liolior three hours, when the oxide of chromium and oxide of iron will have been reduced to themetallio state. On allowing the crucible to cool, or on. emptying the liquid mass into any proper receptacle, it will be found in the form ofa nugget at the bottom of the flux or slag.

In the second I place twenty-five pounds charcoal pig-iron, broken into lumps of six'io eight pounds each, iuto a crucible with twentyfive pounds wrought-iron scraps, to which from one and one-fourth pounds to two and onehelf pounds of the chrome nugget are added. The whole is melted together at a. temperature required for mclbin g steel in the ordinnrysteelfurnaces. This operation will require about; three hours.

-To make e burgle-r-proof safe-box of about three liundredpounds weight, for example, the above melted metal of six crucibles or batches is poured into the ordinary ladle employed by iron-founders generally, and the mold is filled from this ladle. By employing several men to take the pots out of the furnaces and successively pour the metal into the,

mold, so as to maintain an uninterrupted stream entering the orifice of the mold,tl1c ladle may be dispensed with and the ousting cfiectcd directly from the pots.

There are no peculiarities in the mold. They may be made in loom or send, as is generally practiced, or ironmolds may be employed. When these latter are used instead of sand or loam, they should be treated precisely nsis practiced for casting ingots of steel in iron molds-411cc is to say, the inside of the mold should be smoked over a pitchfire, no as to cover it; with a substance resembling lampblack, and heated to from 500 to 600 Fahreu belt, or tbereubout, to prevent the chilling oi the metal as it-is poured into the mold, and thus incur the liability of inj uring the casting.

The quality of wrought or scrap iron is not material. Satisfactory results have been ob.

Room

set forth they are utilized.

'llie'above'is the mode which has been praci.

proceeding as cases powdered "charcoal should be added in is exceedingly hard and will resist concussioncnttingsfrom box-iron employed'by manufa-oin other words, one which is not easily broken ture'rs of fire-safes for braces and ribs of the by a sledge or other means employed for such outer work of the safe. These-punchings and I purposes, and which cannot be perforated or cuttings command onlya low price when sold i cut by the ordinary drill or cutting-instru for scrap-iron, as they are not employed in ments. making steel except for the lower and inferior Having thus qualities of steel; but for the purposes here and the manner in which the same is or may be carried into eifect, I claimtained from the pynchin gs of boiler-plates and ticed; but a similar result may be efi'ected by herein described, the same consisting of chro- .first reducing the chrome ore in the cupola-. mium, cast-iron and wrought-iron,com oundith cast-iron and then ed in the manner andpropor lOllS ereinbefore furnace by mixing it w I has been already described. set forth. Another variation in the mode of procedure 2. The construction of safe-boxes, vaultmaybe effected by adding the'finely-divided chrome ore directly tothe pig-iron and scrap wrought-iron in the crucible, in proportion to the richness of the ore in chromium. In such doors, and other casting the same of the metal .hereinbet'ore described.

In testimony whereof I have signed myname to this specification before two subseribiugwit nesses.

quantity suificient to combine with the oxygen ofthe ore. In this case there is no other variation in process from that already described. l l l WALTER K. MARVIN.

Witnesses:

J os. L. GooMBs,

Emu. F; BROWN.

'From a series ofv experiments I have ascertaiued that the proportions of ingredients described produceavery fine-grained alloy which 1. As a new metal or 'alloy, the composition burglar-proof structures-by described my said invention 

